Dick Burwen's 20,000 Watt Home Hi-Fi System with AUDIO SPLENDORThree of five speaker horns shown

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Dick Burwen's Sound System

Dick started designing the equipment for his current sound system in 1962 and in 2017 it is about finished. His "preamplifier" occupies 3-1/2 racks 7 feet high at the back of his sound studio. In 2009 he disconnected some of the analog tone control units, still in excellent working condition, because they were obsoleted by his new computer digital signal processing system. The small discrete component operational amplifier cubes in the grey panels at the bottom became the basis of Analog Devices' first products in 1966.

The first unit designed was an automatic lighting controller that responds to the music. Mounted in a half-rack outside the left edge of this photo, It delivers up to 20 A at 115 V AC on each of 4 channels. It has been in use 70 hours per week since 1966. Bass is red, middles are green, and highs are yellow. The control circuit boards were redesigned for improved performance in 1982, but the silicon controlled rectifier power stage is the same as it was in 1962.

Each speaker horn has a conical flare and is 13 feet deep. The mouth of each front horn is 8 feet x 8 feet. At the throat, a JBL mid-range exponential horn with a pair of 2440 compression drivers delivers sound between 400 Hz and 6 kHz. An array of 30 Cerwin-Vega tweeters reproduces sound from 6 kHz to 20 kHz. Behind the mid-range horn are two 16-inch Empire woofers covering 15 Hz to 400 Hz. The left front and right front horns each have two 24-inch Cerwin-Vega sub-woofers for frequencies below 50 Hz.

The active crossover network equalizes the speakers. Dick spent a year tweaking its frequency response so that a recording of his son, Russell, playing drums in the front center horn, became difficult to distinguish from the real drums. Below is the crossover frequency response.

Looking down on Dick Burwen's Sound Studio built in 1965-1966, the plan has not changed. He designed it for 5 channels at that time and built his home around it. The left rear speaker horn contains a Lowry organ, now used as a sound diffuser, and the right rear horn holds a 125 year-old Steinway B piano. At the listening sofa the rear speakers deliver reflected sound.

At top are recording mixers for 52 inputs. Bottom playback tone control units are now replaced by 3 powerful laptop computers (1 shown) and MOTU audio interfaces (2 shown).

For 28 years 17 Phase Linear 400 stereo power amplifiers drove the 5 speaker arrays. Together with the 4-way electronic crossover networks, they could produce the same sound level as a single 20,000 watt amplifier. Dick modified these amplifiers for improved frequency response, gain accuracy, and low-frequency power capability. Eventually their power transistors wore out due to thermal fatigue. It would have been OK if the amplifiers simply failed and some power transistors could be replaced. Instead they became intermittent producing a loud pop from the speaker perhaps once a month and later more often. It became too difficult to determine which transistors were failing and in 2004 all 17 units (34 channels) were replaced by QSC SRA 1222 dual 200 watt power amplifiers. Details of the system with Phase Linear amplifiers can be found in the two technical articles that appeared in Audio magazine in 1976 and 1995..

Digital Processing

4-Way Active Crossover Frequency Response

In the early 1970's Dicks analog sound system was built as described in the April1976 Audio magazine article linked below. From a number of attempts at genuine multi-channel recording using one microphone per channel, Dick confirmed that 5-channels made the sound very musical in addition to nicely filling the room and he had made a good decision in designing his sound studio for 5 channels. However, there was a big surprise. He could get an even better effect by starting from a 2-channel recording and processing the signal into 5 channels using microphones, delays, mixing, and equalization. As a result his last 30 years of live recordings were made in 2 channels.

Since his earliest experiments in audio Dick realized that frequency response is the most important aspect of sound quality. His first digital tone control system used Motorola DSP96002 DSP chips on $7500 Ariel DSP-96 circuit boards plugged into a Gateway tower computer. He described how it worked in the April 1995 Audio magazine article linked below. Adding reverberation required a total of 4 DSP-96 boards. To make really good reverberation Dick wished he had 500 times the processing power. When Intel Pentium 4 computers became available, that wish came true.

Dick retired from full time circuit design consulting in September 2002. That allowed him to spend 60 hours per week into 2010 on his passion - improving his sound system via digital audio software. That resulted in his biggest achievement - AUDIO SPLENDOR. This software provides fine control of the frequency response and adds unique high frequency reverberation, unlike that produced by any hall or electronics. For 2-channel sources it adds ambiance into the rear channels and also the front channels. System settings for CD tracks stored as computer files are automatically recalled when playing each file. Now Dick is remastering his 30 years of recordings and able to make them sound far better than when they were recorded. For movies that have explosions in the rear channels he combines 5-channel and 2-channel processing.

AUDIO SPLENDOR software employs 1,400,000 long mathematic equations.

Is the sound system now too old and obsolete? No! At this point in its development Dick is quite happy with its sound. Many of the panels in Dick's racks have been working for more than 30 years with very few repairs. They still perform to today's standards because Dick squeezed highest performance from the many hundreds of integrated circuit operational amplifiers,.most of the electronic parts were of military quality, and highly skilled technicians built them. There is always something to improve, but often Dick enjoys listening at home more than going out to hear music live.